There is no evidence that AntiFa was behind the Capitol riot. Trump's lawyer, Michael van der Veen, did not substantiate his statement.
Michael van der Veen, Trump's defense attorney presented his case, saying Trump was innocent of the charges of inciting an insurrection. Veen instated that the public reports suggested that the "extremists of various political persuasions preplanned and premeditated an attack on the Capitol." After this, Veen alleged, "One of the first people arrested was a leader of AntiFa. Sadly, he was the first to be released." However, Veen did not provide any evidence to support his statement. He did not even name the person that he was referring to.
Following the coverage of arrests after the riot, PolitiFact noted that John Sullivan was arrested on Jan. 14 in connection with the Capitol riot. Sullivan has been described as a controversial, left-wing activist from Utah. He was released from custody on Jan. 15. Although his Twitter accounts show him using #antifa, #blm, and other anti-Trump or anti-police hashtags, Sullivan told PolitiFact that he was not a part of the AntiFa.
NBC News reported on Jan. 9, FBI Assistant Director Steven D'Antuono said on a call to the reporters that there was "no evidence of Antifa involvement in Capitol mob."
AntiFa is short for anti-fascist. AntiFa groups use more traditional forms of community organizing like rallies and protest marches. It is not an organized membership group, but rather groups of loosely affiliated groups that stand against fascism.
FBI Assistant Director Steven D'Antuono also said there was no indication of AntiFa's involvement during the riot.
Logically has previously found that Antifa was not involved in the Capitol insurrection. There is no credible evidence that the individuals who stormed the Capitol were anything other than Trump supporters wanting to overturn the election result.
The impeachment trial concluded on Feb.13 with Trump's acquittal. The U.S government has identified more than 350 suspects and has made 50 official arrests connected to the Capitol riot.